It seems a lot of the times us customers are treated like mushrooms... Kept in the dark and fed on poo.
So for those that dont know, if you use netalyzr there is a good chance you will be able to identify problems not only within your own network but also at virgins end of things also.
I generally use the android app but here is the website: http://netalyzr.icsi.berkeley.edu
When your in the google play store just search for 'Netalyzr'
Hope this helps,